Sulphuric Acid (H2SO4)

Definition - What does Sulphuric Acid (H2SO4) mean?

Sulphuric Acid is a highly corrosive acid available in the market with a molecular weight of 98.079 gram per mole and the molecular formula H2SO4. It is slightly yellowish in color or colorless at times. It is a viscous fluid which easily gets soluble in water at all concentrations. Its historical name is Oil of Vitriol.

Sulphuric acid acts as an oxidizing agent in the crude refining process. Since it also acts as an oxidizing agent in the chemical processes in a refinery, it is also known as an oxidizer. An oxidizer is a chemical compound that helps in transferring oxygen atoms.

Petropedia explains Sulphuric Acid (H2SO4)

Sulphuric acid has a very important role in the Alkylation Unit of a refinery and Fluidized Catalytic Converter Units (FCCU). In alkylation unit, isobutene and low molecular weight alkenes such as butene and propene are converted into an alkylate (iso-octane) in the presence of a strong acidic catalyst such as sulphuric acid or either hydrofluoric acid. Thus in refineries, generally there can be two types of alkylation units installed:

  • Sulphuric Acid Alkylation Unit (SAAU) that make use of sulphuric acid as a catalyst or
  • Hydrofluoric Acid Alkylation Unit (HFAU) that makes use of hydrofluoric acid as a catalyst.

Isooctane which is produced in the alkylation unit with the help of sulphuric acid catalyst serves as a compound that is mixed with gasoline (Motor Spirit or Petrol) to improve its octane number.

The purpose of FCCU in the refineries is to break down higher molecular weight compounds of the crude oil into lower molecular weight alkenes which can be further processed in the alkylation units.
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